The Battle of Fredericksburg pits Union Army of the Potomac under Ambrose Burnside against the Confederate army of Northern Virginia under the famed Robert E. Lee. Burnside had a good concept. He was going to faint on the Confederate Army at Culpeper, Virginia and swing his army to the east, across the Rappahannock River and occupy Fredericksburg. From there he would be closer to Richmond, Virginia than would Lee's army. He could either advance on Richmond or he could push down and seize a great defensive position and compel Lee to attack him. Unfortunately for Burnside, the bridging, the pontoons that would enable him to cross the Rappahannock were late and that enabled Lee to box Burnside's people in. Lee took a great defensive position around Fredericksburg along the high ground. The key positions being Marye's Heights in the upper part of the river and in the lower part, Hamilton's crossing. Burnside thought about pushing farther to the east and swinging across the Rappahannock but he decided not to do it and so he began laying out his pontoons. The Confederates resisted very effectively and it took him an entire day to get people across the river. The next day he moved his entire army across and then he was ready for battle on the 13th of December.

Burnside's concept from a distance was relatively simple and had it been executed and communicated effectively, it might have worked. What he wanted to do was pop through the Confederate army around Hamilton's crossing. Meanwhile the right part of the Union Army was going to seize and hold onto the Confederates at Marye's Heights. The objective was to turn the Confederate right flank. Unfortunately, the battle didn't work out that way. George G. Meade's division penetrated into the Confederate position but he was not well supported. Only John Gibbons division helped out and was able to expand the opening and a major counterattack by Confederate troops drove them out. The bulk of the fighting in the battle actually took place where they were supposed to simply hold the Confederate Army in place, that is Marye's Heights. The Union launched seven assaults on Marye's Heights and they never got close to carrying the position. The Confederates occupied a great defensive line behind a stone wall and in a sunken road. That enabled them to at peak have seven soldiers deep in the sunken road, passing weapons forth and fighting against Union attackers. Furthermore they were supported by 20 artillery guns which laid out very effective fire against the Union troops. In the end about 8,000 Union casualties were suffered at Marye's Heights and in the entire battle about 12,600 Union soldiers were casualties. It was quite a Union disaster. Lee, on the other hand, suffered barely 5,000 casualties. It is a huge number but nothing compared to what Burnside's forces lost.

The Battle of Fredericksburg highlights four very important concepts from a military standpoint. First of all, the defensive power of a rifled musket with a conical shaped projectile was demonstrated clearly at Fredericksburg. The effective range was expanded to three to 400 yards with these weapons and the Union suffered as a result. A second factor was how difficult it is to lay down pontoon bridging in the face of a hostile force. It took the Union an entire day to do so and they suffered quite a few casualties in the process. A third feature of the battle was how difficult it was to fight in the city of Fredericksburg itself. In the Civil War they had linear formations and those aren't well suited to urban fighting and the last major factor with regard to the battle of Fredericksburg was that the Confederates came to the realization that the fortifications were exceedingly valuable in preventing the loss of lives. And so from that point forward, the Confederates began to throw up what they call hasty fortifications, breast works that would protect them from fighting and from that point onward, the Confederates as well as the Federals began to throw them up on the field of battle.